Valve for carburetors



Feb. 8, E A RULL'SON I VALVE FOR CARBURETORS F'led 0617. 7, 1935 INVENTOR furl A. fiM/Ison BY I ATTOR N E! Patented Feb. 8, 1938 UNITED STATES PATENT VALVE FOR CARB URETQRS Earl A. Rullison, Toledo, Ohio, assignor to The Tillotson Manufacturing Company,

Toledo,

This invention relates to valves for carburetion devices and more particularly to air valve carburetion devices.

The invention has for an object the provision of an air valve wherein the valve is of fiat platelike construction cooperating with a valve seat wherein the air valve will admit air to the carburetor yet maintaining adequate suction at the fuel orifice so that a proportionately constant mixture ratio will be maintained throughout a considerable range of engine speeds.

The invention has for further object the provision of a reed or air valve of' simple construction, the valve being of a construction which at all times will form a complete and effective closure without injurious pounding of the seat, and which is formed and arranged to admit a proportionately increasing volume of air maintaining the fuel ratio substantially constant throughout a substantial range of engine speeds.

A further object of the invention is the provision of a flexible air control valve for a carburetor which may be manufactured in large quantities with assurance of a uniformity of product and in which no predistortion of the valve is necessary to insure successful operation and thus enhancing interchangeability of the valves.

Further objects and advantages are within the scope of this invention such as relate to the arrangement, operation and function of the related elements of the structure, to various details of construction and to combinations of parts, elements per se, and to economies of manufacture and numerous other features as will be apparent from a consideration of the specification and drawing of a form of the invention, which may be preferred, in which:

Figure 1 is a side view of the carburetor for housing my invention showing its connection to a fuel supply;

Figure 2 is a top plan view of the carburetor illustrated in Figure l;

Figure 3 is a vertical longitudinal sectional view of the carburetor taken substantially on the line 3-3 of Figure 2;

Figure 4 is an end view of the carburetor showing the air valve mechanism;

Figure 5 is an isometric view illustrating the arrangement of air valve and supporting member;

Figure 6 is an isometric view of the valve supporting member particularly illustrating the spiral valve seat; 1

Figure '7 is a view of modified form of valve disc and supporting member of my invention.

I have shown the arrangement of my invention as embodied in a carburetor of the so-called self-lift type, but it is to be understood that the arrangement may be utilized in any type of carburetion mechanism.

Referring to the drawing in detail, it designates the body of the carburetor which is generally longitudinally cylindrical in configuration, and is hollow to provide a mixing passage H. The carburetor body is formed with a depending boss portion l2 arranged for connection to a fuel supply tank or reservoir I l. 7 This connection, as illustrated, includes a threaded coupling 55, conduit it, the latter having a ball check valve H for a purpose to be hereinafter described, the conduit projecting substantially to the bottom of the fuel supply tank M. One end of the carburetor body it is formed with a cylindrical portion which extends into the extremity of an intake manifold 25, the latter communicating with the cylinders of an internal combustion engine (not shown). The other end of the carburetor body is formed with an en larged cylindrical portion 23 arranged to accommodate a conduit or air horn 2 5 which may be formed as a part of an air cleaner or the like (not shown).

The interior of the depending boss portion 3 vided with a kerf or slot 29 adapted to receive a screw driver or other suitable tool for positioning the fitting 21 in the threaded bore in boss l2. The upper portion of the bore in the boss l2 accommodates a fuel nozzle structure 36 having a shoulder Bl which rests against a flange rormed at the end of the bore in the boss 12. The fitting 27 when threaded to the position shown in Figure 3 contacts with a lower portion of nozzle 3!! to hold the latter in fixed position in the carburetor body.

The nozzle structure is formed beneath the flange 32 with a reduced portion in such a manner as to provide an annular space 33 which communicates with a chamber in the carburetor proper adjacent the base of the venturi by means-of a passage way 34. The wall of the chamber 33 formed by a portion of the nozzle structure is provided with small horizontally extending openings 31 so that air may be ad- Lil mitted under certain conditions to the fuel before its extrusion from the nozzle by means of the passage way 34 and openings 31, thus providing a suitable air bleed, the purpose of which will be hereinafter explained.

The carburetor body I 8 is provided with a boss 35 having a threaded bore 36 in alignment with the axis of the nozzle 30, the bore 36 receiving a threaded member 38 associated with a needle or metering pin 39 having a tapered extremity 40 adapted to be received into bore 28 of fitting 21. The member 38 is provided at its upper extremity with a knurled knob 42 and interposed between the knob and boss 35 is a spring 44 serving to exert suflicient friction between the threads of member 38 and those in the boss 35 to hold the needle or metering pin 33 in adjusted position. By rotating the knurled knob 42, the needle 39 may be adjusted relative to fitting 21 to regulate the amount of fuel passing through the orifice or passage 28 in the fitting, consequently regulating the amount of fuel passing through the nozzle 30. It is to be noted that the inner bore of the nozzle 38 is larger than the diameter of the needle 39 so as to provide a space 4| for the passage of fuel mixture.

Positioned interiorly of the carburetor body in the mixing passage is a Venturi tube 45 which is arranged so that the nozzle 30 projects through an opening in one wall of the Venturi tube, the latter preferably having its maximum point of restriction near the fuel exit of the nozzle 30 so that the maximum. velocity of air passing through the mixing passage will occur approximately at the point of discharge of fuel from the nozzle 30.

Positioned between the Venturi tube and the exit of the mixing passage is a throttle valve in the form of a circular disk which is carried upon a shaft 5! secured thereto by means of a screw 52 or other suitable means, the shaft being journalled in bosses 53 and 54 formed on the carburetor body. An arm 49 is secured to the shaft 5i for manipulation thereof to regulate or control the amount of fuel and air mixture supplied to the engine. The end of the shaft 5| adjacent boss 54 is provided with a tenon 55 of non-circular configuration which carries an arm 56, the latter having perforations 51 adapted to selectively receive the extremity of a coil spring 58. The carburetor body is provided with a boss which forms a support for a plate 6| secured thereto by means of screws 62 and 63, plate 6| having a series of openings or perforations 64, one of which is adapted to receive the other extremity of the coil spring 58. The arm 49 in certain installations is connected by means in the form of a link 48 to a governor mechanism or other automatic speed controlling means which may be associated with an engine. Thus, in the present embodiment of the invention, the spring 58 therefore tends to urge the throttle to open position, its maximum opening movement being limited by means of screw 41, and the governor under the influence of an increase in speed of the engine tends to close the throttle valve causing a corresponding decrease in the quantity of fuel mixture, thereby reducing the engine speed. The tension of spring 58 may be varied by shifting the connections of the extremities of the spring to another of said perforations or different lengths and sizes of springs may be used in various installations to obtain proper governor controlled compensation. In this manner, any desired tension may be had urging the throttle valve toward open position.

A disk valve 66 secured upon ashaft 61 forms a suitable choke or manually operated means to control the air supply admitted to the carburetor. This control in the embodiment illustrated consists of a flexible sheath 68 which encloses a wire or cable 69 connected to the end of an arm 18 carried by shaft 61, the wire being conveyed by means of the sheath to a convenient operating location (not shown). The sheath or guide 68 for the flexible wire control is secured by means of a clip H held in place by means of screw 62.

The invention comprises an air valve for controlling the supply of air to the carburetor in proportion to the speed of the engine with which it is connected. This arrangement in the embodiment illustrated comprises a valve support in the form of a disk 15 having air passages or openings I6 and 11, these passages being normally closed by means of a flexible annular disk or reed valve 19, the same being particularly shown in Figures 3 and 5. The valve 19 is preferably fabricated of a flat sheet of material. A supporting disk 15 is formed with a valve seat which is preferably of a spiral configuration reaching its highest point adjacent the unattached extremity of the valve 19 as illustrated in Figures 5 and 6, the same being fixedly retained in position upon disk 15 by means of screws 82. I have found in practice that a rise of between ten-thousandths to twenty-thousandths of an inch from the free end of the valve with respect to the secured end functions satisfactorily when used with ordinary engines. The valve disk is fabricated of comparatively thin steel or similar material having a flexibility that will be acted upon by the suction or decreased pressure of the air in the carburetor whereby the valve is opened by such differential in air pressure during engine operation. Thus, in this form of my invention, a predistortion of the reed valve is not essential as the stress is placed upon the valve by the spiral rising valve seat 80, and the valve reed 19 will fit tightly against the seat 80. The supporting disk 15 may be held in place in the end of the carburetor by suitable means as, for example, a snap ring 85. The disk 15 is preferably provided with a small opening 86 for the purpose of relieving pressure which may be set up by reason of a backfiring condition of the engine through the carburetor. This opening serves the purpose of partially relieving back pressure set up in the carburetor by reason of the back firing of the engine and tends to prevent such back pressure driving or forcing the fuel in the supply pipe I6 downwardly into the fuel reservoir.

Figure 7 illustrates a modified form of the invention wherein the valve support or seat 90 has a uniplanar valve seat surface having an opening 80' for the admission of air which passes the valve disk 9|, the parts being shown in disassembled relationship. The valve disk BI is similar in construction to valve disk 19 hereinabove described except that the disk is preferably preformed in a spiral configuration as illustrated so as to impart a stress in the movable portion of the valve disk. In this manner, the disk will be held against the valve seat or support by the inherent stress or tension in the disk. The one extremity of the valve disk is held in position upon the valve seat or support by means of screws (not shown).

The operation of the air valve of my invention is as follows:

When an internal combustion engine with which my invention may be utilized is started, the reciprocation of the piston or pistons in the engine sets up suction which will elevate fuel from the fuel supply reservoir past the check valve blank through the nozzle 39 into the mixing passage in the carburetor body. During this starting operation, the choke or manually operated valve 66 is in closed or partially closed position so that the engine suction is highly effective to elevate the fuel. When the engine has started, the choke 66 is opened with a consequent decrease in pressure behind the valve 19 below atmospheric pressure and due to this lower pressure, the reed valve 19 moves inwardly and is distorted to admit air through the air entrance 2 1 into the mixing passage in which passage due to the velocity of the air column moving through the venturi 45 of the mixing passage fuel from the nozzle 30 is mixed therewith, which mixture passes into the internal combustion engine. As the speed of the engine increases, the velocity and volume of the air passing through the mixing chamber of the carburetor will be increased as there is additional vacuum or decreased pressure created within the mixing passage, this differential in pressure acting upon the air valve or reed l9 and causing the latter to be opened a proportionately greater distance to admit additional air supply. The velocity of such incoming air as the engine speed increases is also increased and a proportionately increased amount of fuel will be taken into the mixture through the nozzle 30 whereby there is maintained a substantially constant proportion of the amount of fuel to air passing through the carburetor which is maintained throughout a substantial range of speed of the internal combustion engine. I have also found that my invention when utilized with an internal combustion engine of a single cylinder or twin cylinder type or with an engine wherein there exists a substantially intermittent suction due to piston movement upon the carburetor that a mixture ratio is maintained giving the engine a high degree of operating efiiciency. I have found that at comparatively high speeds the proportion of fuel taken into the air stream is slightly enriched, and to decrease this tendency toward enrichment, the nozzle is air bled by means of the air bleed channel 34 leading from a point adjacent the forward end of the Venturi tube into the side wall of nozzle 36 ahead of its discharging point into the mixing passage. By this means, air is admitted to the fuel prior to its extrusion from the jet which provides more or less of an air and fuel emulsion being extruded from the jet at comparatively high engine speeds, and due to such prior admission of air into the fuel column, I have found that the tendency of the mixture to become over-enriched at such high engine speeds is substantially eliminated. Thus, I have provided an arrangement whereby a desirable fuel mixture is supplied to an internal combustion engine by the use of an arrangement having only one moving part, viz., the reed air valve. in event of backfire of the engine, the ball check ll prevents the fuel from being driven downwardly into the fuel reservoir M.

It is apparent that, within the scope of the invention, modifications and different arrangements may be made other than is herein disclosed, and the present disclosure is illustrative merely, the invention comprehending all variations thereof.

What I claim is:

1. An air valve for carburetors including an element having a port therein; a valve seat surface formed on said element adjacent said port; a valve member of split annular configuration having an end portion secured to said seat element and being otherwise free to form a flexible Valve portion; said valve seat surface being helically arranged whereby said portion of said valve member may be flexed from the element for the passage of air through said port.

2. An air valve for carburetors including a disc like support member having a port therein; valve means comprising a flexible annularly shaped split member; means to secure one end of said flexible member to said support, the other end of said flexible member being free to flex; a valve seat formed on said support adjacent the port therein and helically arranged with respect to the normal plane of said support; said valve means and valve seat cooperating to form a variable opening for the passage of air through said port.

EARL A. RULLISON. 

